Anhydrous Catalyst Research Articles

Acquisition of para-(1-methylcyclopentyl)phenol and its acylation reaction with acetyl- and benzoyl chlorides

The article is devoted to the study of phenol cycloalkylation reactions 1-methylcyclopentene in a in periodical action installation in the presence of zeolite-containing catalyst KN-30 and acylation reactions of obtained p-(1-methylcyclopentyl)phenol with acetyl and benzoyl chlorides in the presence of a ZnCl2 catalyst. First of all, the influence kinetic parameters (temperature, time, molar ratios starting components, the amount of catalyst) on the yield and selectivity reactions of cycloalkylation of phenol with 1-methylcyclopentene in the presence of catalyst KN-30 was investigated. In the found optimal conditions for the cycloalkylation reaction: temperature – 110 оС, time – 5 hours, molar ratio of phenol to MCF 1:1, amount of catalyst 12 %, yield of the target product – p-(1-methylcyclopentyl)phenol is 77.3 % (based on phenol), the selectivity of the target product is 92.6 %. Acylation reactions of the obtained p-(1-methylcyclopentyl)phenol with acetyl- and benzoyl chlorides were performed in the presence of anhydrous catalyst ZnCl2. In order to obtain effective conditions for acylation reactions, the influence of the reaction temperature, duration, and molar ratio of the starting components on the yield and selectivity of methylcyclopentylaceto- and benzophenones was studied. As a result, it was found that for acylation reactions of p-(1-methylcyclopentyl)phenol with acetyl and benzoyl chloride in the presence of a ZnCl2 catalyst, the reaction temperature is 140–150 оC, the duration should be 35–40 minutes, and the molar ratio phenol AC(BC) should be 1:2. Under these conditions, the yield of target products is 57.2–61.7 % (based on the taken alkylphenol).

Highly Diastereoselective Chelation-Controlled 1,3-anti-Allylation of (S)-3-(Methoxymethyl)hexanal Enabled by Hydrate of Scandium Triflate

En route to the total synthesis of (+)-Neopeltolide, we explored Lewis acid-assisted diastereoselective allylation of MOM-protected 3-hydroxylhexanal with β-(2,2-diethoxyethyl)-substituted (allyl)tributylstannane. The hydrated form of scandium triflate was found to be essential for attaining high 1,3-anti-diastereoselectivity (d.r. 94:6), while the use of anhydrous catalyst resulted in a modest diastereocontrol (d.r. 76:24). The preferred 1,3-anti-selectivity in this transformation can be rationalized in the framework of the Reetz chelate model of asymmetric induction. The 1,3-anti-configuration of the product was confirmed by its conversion into the known C7-C16 building block of (+)-Neopeltolide. We also report an improved protocol for the synthesis of β-(2,2-diethoxyethyl)-substituted (allyl)tributylstannane, which can be utilized as a cost-efficient bipolar isoprenoid-type C5-building block in the synthesis of natural compounds.

Effect of solvent on catalytic performance of anhydrous catalyst in acetylene dimerization to monovinylacetylene

The production of monovinylacetylene (MVA) through Cu(I)-catalyzed acetylene dimerization reaction was performed in different reaction media. Based on the analyses of crystals precipitated from the catalyst solution and UV-Vis spectra of the catalysts, the reaction mechanism and solvent dependence were studied. The highest yield of MVA can be obtained when dimethylformamide is used as solvent because of its strong coordination ability to Cu(I). The activation of C≡C bond is presumed to be improved when the catalytic metal ion is coordinated by a solvent with less steric hindrance and electron-rich coordination atom. The results of the present study provide a possible way to accelerate the metal-catalyzed homogeneous reaction of alkyne substrates through careful selection of a solvent.

ChemInform Abstract: Synthesis and Biological Evaluation of Some Pyridazinone Derivatives

AbstractReview: 61 refs.

Studies on the Catalytic Performance of the Nieuwland Catalyst and Anhydrous Catalyst in the Dimerization of Acetylene to Monovinylacetylene

The present work aimed to find reasons for different catalytic ability of the Nieuwland catalyst and anhydrous catalyst in dimerization of acetylene to produce Monovinylacetylene (MVA). The results showed the catalytic ions in the Nieuwland catalyst and the anhydrous catalyst were CuCl-2 and Cu2Cl-3 respectively by studies on the Cu-containing crystals recovered from corresponding catalyst. CuCl-2 in crystal A and Cu2Cl-3 in crystal B has similar crystal structure, however, Cu(Ι) in Cu2Cl-3 has higher electron density due to stronger bond energy of Cu(Ι)-Cl, which may contribute to the higher activity of the anhydrous catalyst than that of Nieuwland catalyst.

Improvement of anhydrous catalyst stability in acetylene dimerization by regulating acidity

AbstractBACKGROUND: Loss of the active CuCl component occurs during acetylene dimerisation to monovinylacetylene (MVA) catalysed by an anhydrous catalyst with the formation of a dark red precipitate. Acidic species can reduce the loss of CuCl but have an unfavorable influence on acetylene dimerisation. This study aims to determine the precipitate composition and regulate the acidity of the catalyst to find a balance between reaction rate, MVA selectivity and catalyst life.RESULT: The precipitate composition was 2CuCl·3C2H2·1/3CH3CH2NH2·1/7C3H7NO, formed by the combination of DMF, CH3CH2NH2, C2H2 and the [Cu]‐acetylene π‐complex, which is an intermediate in the reaction. From an overall consideration of the loss of CuCl, conversion of acetylene, and selectivity of MVA, the reaction temperature and acetylene space velocity were optimized at 65 °C and 200 h−1, respectively. The introduction of HCl into the catalyst with a rate of 3.2 h−1 could reduce CuCl loss by 73.5%, whereas conversion of acetylene was only lowered by 9.0%.CONCLUSION: Acidity regulation of the anhydrous catalyst by optimising the reaction temperature, acetylene space velocity, and rate of addition of HCl shows little negative effect on acetylene conversion and selectivity to MVA but can reduce CuCl loss significantly. © 2012 Society of Chemical Industry